DESCRIPTION: Understanding the emerging knowledge of object categorization is a key aspect of cognitive development and conceptual organization. How does category knowledge develop in infants and toddlers? Recent research suggests that, by the age of nine months, infants' category learning is facilitated by words. The areas of inquiry described in this project extend these findings in two directions. One aim is to test the idea that infants are predisposed to connect language labels to categories by examining how infants respond to words paired with objects compared to other sounds paired with objects. Infants' attention to objects and labels (or other sounds) is examined in a category learning task that measures (a) traditional behavioral responses, such as object exploration, as indicators of attention and preference and (b) heart rate change as an indicator of attentional reactivity and regulation. These proposed studies focus on the developmental period between 7 to 11 months. The other aim is to begin to examine the cues for the connections between object categories and language provided in the infant's environment. The proposed studies of parent-infant structured interactions with objects are designed to describe how parents use language and other cues to direct infants' attention to category relations and, importantly, how those cues change as the infants mature. These proposed studies span the developmental period between about 6 and 24 months. The ultimate objectives of this research are to understand how the fundamental processes of categorization emerge from developing language and cognitive competencies in infancy, and how adults provide support for these emerging abilities. Discovering how basic cognitive abilities unfold and are acquired is integral to our understanding of normal, healthy development in the first few years of life. In addition, such developmental studies provide age-related expectations for normal cognitive accomplishments and may be used both to provide recommendations for supporting such competences and to inform assessment of atypical or at-risk development.